First, under section 1021(d), the bill does not "limit or expand the authority of the President or the scope of the Authorization for Use of Military Force." Second, under section 1021(e), the bill may not be construed to affect any "existing law or authorities relating to the detention of United States citizens, lawful resident aliens of the United States, or any other persons who are captured or arrested in the United States." My Administration strongly supported the inclusion of these limitations in order to make clear beyond doubt that the legislation does nothing more than confirm authorities that the Federal courts have recognized as lawful under the 2001 AUMF. Moreover, I want to clarify that my Administration will not authorize the indefinite military detention without trial of American citizens. Indeed, I believe that doing so would break with our most important traditions and values as a Nation. My Administration will interpret section 1021 in a manner that ensures that any detention it authorizes complies with the Constitution, the laws of war, and all other applicable law.

Many have heard that Obama has signed the NDAA law. Not many have read his attached comments to the signature. My research on the matter has led me to believe that he was once again outplayed by Republicans and forced to sign something that had a ton of good stuff in it that he basically couldn't veto.

Here's a good explanation: http://www.reddit.com/r/politics/comments/nxu96/obama_signs_ndaa_with_signing...